The invention relates to an elevator installation having at least one car which is vertically movable upwardly and downwardly by means of a linear motor, the linear motor having stationary primary parts and a secondary part which is fixed to the car.
Conventional elevator installations generally have a car which is vertically movable upwardly and downwardly in a shaft, and is driven by a driving pulley over which a traction cable that connects the car to a counterweight is guided. These types of elevator installations have proven successful in practice. Elevator installations are also known in which the car is hydraulically driven. However, due to technical and economic reasons, their use remains limited to relatively low lifting heights.
It has previously been proposed, in particular for elevator installations for very high buildings, to use cars which are directly driven by means of a linear motor, without a cable. In these types of elevator installations, counterweights as well as traction cables may be dispensed with. This has the advantage that the masses to be accelerated may be kept low during an empty trip, so that the car may be moved at high speed and high acceleration, thus keeping waiting times short. The linear motor has stationary primary parts fixed in the shaft, which cooperate with a secondary part fixed to the car. For example, the secondary part fixed to the car may be configured in the form of exciting magnets, and the primary parts fixed in the shaft may be provided in the form of stator windings. To achieve a high efficiency of the linear motor, an air gap between the secondary part and the primary parts should be kept as small as possible. This requires exact guiding of the car, as well as precise mounting of the primary and secondary parts of the linear motor.
Heretofore, efforts to implement a technically and economically satisfactory solution for the use of a linear motor in elevator installations have not been successful. The arrangement of a functional part of the linear motor on the shaft walls and on the car, including the necessary assemblies for power supply and control, as well as the precise guiding of the car for maintaining the smallest possible air gap between the primary and secondary parts, represents a very high demand on the manufacture and erection of the elevator installation. Difficulties also arise due to the dynamic and parasitic forces of the linear motor that prevail between the primary and secondary parts. Such demands and difficulties ultimately result in complex erection operations over the entire height of the shaft.
It is an object of the present invention to improve an elevator installation of the type mentioned at the outset in such a way that it allows simpler installation.